Protect 2 (Figure 8)
Protect 2 monitors the circuit feeding the 3.3V standby supply.
In the standby mode, the +33V supply will measure approximately 8 volts. When the set is
turned On, it will go to +33V as the power supply goes to a full power mode. Q635 regulates
the voltage feeding IC631, AL3.3V regulator.
If Q635 fails, the voltage at the emitter of Q635 would exceed the voltage of the 10 volt zener,
D407 causing it to conduct. This will cause the PROTECT 2 line to go High resulting in the
TV set turning Off.
FIGURE 8 - PROTECT 2